Role of Lactose in Pharmaceuticals


Lactose is a naturally produced simple carbohydrate or sugar that can only be seen in mammalian milk. It is also known as “milk sugar” or “lactose powder.” All industrial lactose is derived as a by-product of the dairy sector from pasteurized milk.

bottle, milk, drink
Foundry (CC0), Pixabay

Lactose is a disaccharide derived from the natural sugars D-galactose and D-glucose. In other words, one molecule of D-galactose is chemically connected to one molecule of D-glucose in the lactose molecule. Lactose is divided into two isomeric forms: alpha and beta (designated a-lactose and b-lactose).

Pharmaceutical-grade lactose is ultra-pure lactose prepared to meet the various pharmacopeia lactose prescriptions’ strict authenticity and purification requirements. Lactose is commonly employed as an additive or diluent in solid oral dosage forms and lyophilized goods, newborn feed formulas, and as a solvent in dry-powder inhalations to a lesser extent.

Excipient Properties of Lactose 

Lactose is commonly utilized in the production of pharmaceutical tablets and capsules as a filler or filler-binder. Lactose’s general qualities, which add to its attractiveness as an excipient, include; cost-effectiveness, accessibility, bland taste, low hydrophobicity, compatibility with bioactive compounds and other additives, excellent physical and chemical integrity, and water solubility.

Pharmaceutical Applications

To produce tablets or capsules, you must first prepare a mixture of excipients and active components. This mixture is referred to as the running powder in its ultimate state, as the tablet press or capsule filling feed material. To separate the components of the flowing powder, three basic procedures are used: Wet granulation, dry granulation, or slugging, and dry mixing.

  • Wet Granulation

The binder can be applied dry to the powder blend or as a solution in the solvent for wet granulation. Typically, the solvent is alcohol, water, or a combination of both. The actual sifting takes place in a high-shear or low-shear type mixer.

Low-shear milling uses less expensive equipment and creates more porous granules. High-shear granulation is quicker and allows for better crystallite size control.

The finer processed grades are widely employed as fillers in the wet granulation manufacturing of tablets or applications requiring a small particle size. When the viscosity is critical, the coarser sifting grades are used as diluents in tablet and sachet filling procedures as flow stabilizers.

Some sifting grades are also utilized as fillers in granulation and direct compression compositions. However, they must be combined with a binder because crystalline a-lactose monohydrate has limited compactness.

Another form of the method is fluid bed wet granulation, which involves coagulation and drying in the same barrel (a fluid bed granulator). Dry air inside a compartment fluidized the powder mix. To make the agglomerates, the binder solution is poured onto the fluidized powder.

The air fluidization process continues till the agglomerates are dry. This technique is expensive, but it is easier and generates a porous low-density granule, which can help drugs dissolve faster. Since this active component is bound into the granule and early tablet fragmentation liberates the particles rather than the primary drug particles, slow drug dissolution is occasionally a concern related to wet granulation.

  • Dry Granulation 

Crystallite size amplification is accomplished in dry granulation by combining powder particles under increased pressure (compaction) and then processing the compressed product to the required size. The milling fines are re-circulated through the compactor.

The compression process is usually done in a roller compactor, which compresses the particles amid two rollers. Since there is no additional physical or chemical alteration before tableting, the major flowing powder requirements (primarily blend uniformity, constant bulk density, flow, and compactness) must always be met by the dry mix of excipients in direct compression.

As a result, the excipients’ morphological and physiological qualities, notably the filler-binder, are critical and must be constant from batch to batch. Drying a lactose solution over the surface of a heated drum produces anhydrous lactose for direct compression.

This creates a product made up of agglomerated minute particles of anhydrous b-lactose with a minor amount of anhydrous a-lactose. Due to its high b-lactose concentration, the anhydrous product has outstanding compactness and solubility.

Different Lactose Grades

Varied lactose varieties with different physical attributes, such as particle size distribution and dynamic viscosity, are commercially viable. Crystalline a-lactose monohydrate is the most frequent type of lactose used in pharmaceutical manufacturing.  It comes in various crushed and filtered pharmaceutical grades with different physical attributes like wettability, hydraulic conductivity, and particle size.

Lactose is also accessible in modified forms to be used as a filler-binder in the direct compression technique of tablet manufacturing. Spray-dried lactose and anhydrous lactose are the two most common types for this purpose. These forms have the critical virtue of being inherently compact and can be compressed into a solid compact called a tablet.

What is Lactose Monohydrate?

A lactose monohydrate is a molecule that occurs naturally in milk. It is manufactured as a powder and utilized as a sweetener, stabilizer, or filler in the nutraceutical and cosmetic sectors due to its chemical structure. Pills, infant formulae, and packaged sweet meals all have it in their ingredient lists.

Lactose monohydrate is the crystallographic form of lactose, which is the primary carbohydrate found in pasteurized milk. Lactose is made up of two natural sugars linked together: galactose and glucose. There are two types of lactose: alpha- and beta-lactose, which have different molecular structures.

Lactose monohydrate is made by heating alpha-lactose using pasteurized milk until the crystalline phase appears, then drying off any extra liquid. The outcome is a dried, white or pale yellow powder with a slightly sweet flavor and a milk-like odor.

Lactose Monohydrate Uses 

It is frequently employed as a food ingredient and filler in pharmaceutical capsules. It is primarily used in industry and is not usually offered for personal usage. As a result, you might see it on nutrition labels but not in recipes.

Lactose monohydrate and other fillers bind to the active ingredient in a medication, allowing it to be shaped into a pill or tablet that can be ingested easily. Lactose is included in about twenty percent of prescription pharmaceuticals and over sixty-five percent of over-the-counter medications, including birth control pills, vitamin supplements, and acid reflux treatments.

Lactose monohydrate can also be found in newborn formulae, canned goods, frozen meals, and packaged cookies, cakes, patisserie, soups, and sauces, among other things. Its principal function is to sweeten or act as a stabilizer, allowing materials that do not blend to stay together, such as oil and water. Lastly, lactose monohydrate is commonly used in animal feed since it is a low-cost technique to boost meal volume and weight.

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